1. Field of the Invention
The present invention relates to a subrack comprising a motherboard, a plurality of logic cards in a planar disposition, first cooling members assigned to each of the logic cards, and second cooling members to which all first cooling members are releasably attached in common.
2. Description of the Prior Art
Increasing miniaturization of integrated modules and a high packing density have resulted in a great heat emission from the modules which can easily lead to transgression of the permissible module temperatures. For purposes of cooling by convection to the surrounding air, it is known from the German published application 23 47 751 to respectively provide logic cards, planarly plugged onto a motherboard, with a large-surface metal plate which is in thermal contact with the modules. With its one side directed towards the outside, it is embedded -in a plug connector encompassing the logic card.
Known, further, from U.S. Pat. No. 3,993,123 is a cooling device for one or more heat-emitting electronic modules which are contacted to one side of a flat carrier. The modules are disposed with thermal contact below a thermally-conductive cap to which a cooling member traversed by a coolant and terminating nearly flush with the carrier is flanged. When, however, a larger plurality of such devices is disposed on a printed circuitboard, then an at least correspondingly large plurality of line sections must be provided in order to guarantee the supply of all coolant circulations. This, however, can require a considerable expense for assembly and maintenance.
Further known from the German published application 29 26 076 is an arrangement for cooling electronic modules wherein the stray heat is diverted over thermally-conductive paths of a carrier card onto a plug-in frame which accepts a plurality of cards in a parallel disposition and is dissipated from the plug-in frame onto a housing wall which serves as a cooling member. For supporting and covering, the plug-in ring surrounds a structure which is put in place on the housing wall and inside of which springs are supported against the plug-in frame such that the frame is pressed against the housing wall. As a result thereof, however, long heat transfer paths and a plurality of heat transfers arise, so that the cooling effect is relatively low. Moreover, the danger also exists that the thermal contact between the frame and the housing wall will be interrupted given mechanical shocks since it only depends on the spring forces which, however, cannot be arbitrarily high in consideration of the mechanical stability of the structure.